Which instrument sounds down a major sixth plus one octave from written treble?

• A. Eb alto clarinet
• B. Bb bass clarinet
• C. Oboe
• D. Eb contra alto bass clarinet

Answer: (D)

Understanding transposition is the key. Some woodwinds are written a different pitch than what they sound. The alto clarinet in E-flat sounds a major sixth lower than written. If you take that idea and move to a instrument labeled contralto (one octave lower than the alto), the sounding pitch shifts down another octave. So this instrument sounds a major sixth lower plus an octave, which is a thirteenth interval overall. In other words, written treble notes will sound about thirteen semitones lower, matching the description of “down a major sixth plus one octave.” That’s why this instrument is the correct choice.

The other options don’t fit this exact interval: the alto clarinet alone lowers by a major sixth, not an octave more; the bass clarinet lowers by a major ninth (an octave plus a second); the oboe stays at concert pitch, sounding as written.